The influences of age and gender on blood ethanol concentrations in healthy humans.

Objective: Previous cross-section studies suggested that blood ethanol concentrations (BAC) increase with age. To establish this, and to account for putative gender differences, we studied four cohorts of nonalcoholic subjects.
Method: Fifty-seven subjects were studied: 14 men and 14 women in the young (21-40 years) and 14 men and 15 women in the old (> or = 60 years) groups. All subjects received ethanol (0.3 g/kg) on three occasions: orally (PO) after an overnight fast; PO after a standard meal; and by intravenous (IV) infusion after a standard meal.
Results: In all four cohorts, PO ethanol in the fasted state produced the greatest average areas under the curve (AUC) for ethanol, followed by IV ethanol and PO ethanol, both in the fed state. Pooled by age, blood ethanol AUCs were significantly greater in old subjects given PO ethanol when fasted (p = .001) and IV ethanol when fed (p < .004) but not after PO ethanol in the fed state. Pooled by gender, blood ethanol AUCs did not separate men and women in any of the experiments. Corrected for relative volumes of distribution (Vdist) among the four cohorts, only elderly women evidenced AUC values that could not be explained by Vdist alone and only in the fasted state. Both elderly men and women in the fasted state showed higher average peak ethanol levels than gender-matched younger cohorts; this effect was most pronounced in elderly women (47% vs 12%).
Conclusions: The data confirm the influence of age, but fail to confirm that of gender, on blood ethanol response after a moderate dose of ethanol. They also show that feeding state can negate differences due to Vdist alone. In the fasted state, Vdist alone explains AUC and peak increases in elderly men but not in elderly women. Neither gastric metabolism nor motility account for age/BAC differences since these were independent of route. These data suggest caution for elderly drinkers or for those prescribing alcoholic beverages to elderly persons as well as for studies of ethanol ingestion that do not account for age and for feeding state.